Improvement in treating wood to imitate manila-paper pulp



UNITED TATES AT NT OFFICE.

GEORGE E. MARSHALL, OF TURNERS' FALLS. MASSACHUSETTS.

IMPROVEMENT lN TREATlNG WOOD T0 IMITATEMANILA-PAPER PULP.

- Specification forming part of Letters Patent No. 207, i28, datedAugust 27, 1878; application filed July 12, 1878.

To all whom it may concern Be it known that I, GEORGE E. MARSHALL, ofTurners Falls, in the county of Franklin and Commonwealth ofMassachusetts, have made a new and useful Improvement inthe Process ofPreparing Wood for Wood Pulp, to be used in-the manufacture of animitation of Manila paper; and that the following is a clear and exactdescription of the same.

This invention relates to that class of processes in the preparation ofwood pulp for the manufacture of paper where the resin, gum, and otherdeleterious substances are dissolved and partially removed by mechanicalmeans; and consists in applying heated water under a pressure many timesgreater than would be produced by the heat employed? It is wellunderstood that mo& of the wood for wood pulp, being necessarily cut inthe winter, becomes dry, hard, and seasoned be: fore it can be used, andthe resin, gum, andother foreign substances become solidified andfixed.To remove these substances, and to bring the wood thus dried andhardened to a suitable condition to be worked, various methods have beenemployed, some mechanical, by long boiling in open vats, or bysubjecting the wood to a high degree of steam-heat; some chemical, byboiling it in an alkali, which requires the wood to be afterwardbleached, and others, all of which are in some way objectionable, eithertedious or expensive, or both, and often fail to accomplish the desiredresult.

I purpose to prepare the wood for use by the action of hot water under aheavy pressure.

The wood, having been cut, split, and prepared in the manner common forsuch use, is

' placed in a close vessel or tank, made tight and strong enough toresist a pressure, it necessary, of four hundred and fifty pounds to thesquare inch, and is closely packed. At the bottom of this tank is anopening with a valve through which the water, previously heated to apoint above boiling and below 280, is forced by a hydraulic press tosuch an extent as to saturate and to completely permeate the wood, andto soften and to drive out of the pores the gum, resins, and acids; andif the temperature is kept sufficiently hot, it gives the pulp thedesired color belonging to a finely made Manila paper. This may be aidedsomewhat by the introduction of a small quantity of some alkalinesubstance to act on the acids.

The water maybe heated in a coil outsidc and forced into the tank by ahydraulic press. The water thus heated and forced in leaves the wood forthe pulp in the most desirable condition for work and for color.

Pulp made from wood treated below the boiling-point will be white; but Isecure the desired Manila color by raising the tempera ture to 240 or250 for a light Manila, and as high as 280 for a dark pulp.

In my patent of'July 17, 1877, I emptcryed'a part of this process; butthat was for the preparation of pulp for white paper only,and would notaccomplish the purpose of the present application, which is to leave thepulp strongerv and of the color desired for my use.

I wish it distinctlyunderstood that my process differs from any other inthis, that a l though 1;. have water-heated above the boilingpoint andunder pressure, yet the pressure within the tank is-by the mechanicalaction of the hydraulic press, and not due to the expansiveforce ofsteam, No pressure is required from the steam above three atmospheres;but the press may give from four hundred and fifty tofive hundred poundstothe square inch, and practice has shown that the greater the pressurethe more speedy is the operation on the wood. I

I claim Preparing wood for an imitation M anilapaper pulp by the processabove described, substantially in using water at a degree of heatbetween 212 and 2809, and under a very heavy hydraulic pressure, bywhich the wood is brought to a proper condition to work and the desiredcolor obtained for the pulp.

eno. n ARsHALL.

Witnesses:

W. D. RUssELL, PORTER FARWELL.

